1. Field of the Invention
The present invention relates to a multi-shaft turret type winding device for winding a thin layer band material such as a plastic film.
2. Description of the Related Art
Various winding devices for winding a thin layer band material such as a plastic film have been conventionally proposed. A Multi-shaft turret type winding device having a plurality of winding, mandrels and continuously winding a thin layer band material is one of the conventional devices.
As shown in FIGS. 6A through 6C, Japanese Published Application (KOKOKU) No. 39303/1994 shows one example of a conventional multi-shaft turret type winding devices. The multi-shaft turret type winding device is capable of winding a plastic film.
In FIG. 6A, winding mandrels (i.e. two winding mandrels) 102a, 102b are provided, respectively, at the ends of a swingable turret arm 101. A plastic film 103 can be wound at a winding position C by one of the winding mandrels 102a while a touch roller 104 contacts a wound plastic film (hereinafter referred to as a "product roll") 103'. The touch roller winds the plastic film 103 while maintaining an appropriate winding angle .alpha. and pushes the plastic film 103 toward the product roll 103'.
The plastic film 103 is supplied through a guide roller 105 and wound on the product roll 103' while the plastic film 103 is contacted with the touch roller 104 at an appropriate winding angle. The plastic film 103 is wound around the winding mandrel 102a.
Air is prevented from being introduced into a portion between the layers of laminated plastic film of the product roll 103' so that wrinkling of the product roll 103' caused by the introduction of air and improper winding is prevented.
When a winding amount of the product roll 103' on the winding mandrel 102 reaches a predetermined amount at a normal winding position C, the turret arm 101 is rotated as shown in FIGS. 6B and 6C so as to change from the winding mandrel 102a to the winding mandrel 102b. The plastic film 103 is cut, and a cut edge of the plastic film 103 is wound around the winding mandrel 102b which is newly positioned at the winding position C. Thus, the plastic film 103 is successively wound around the winding mandrel 102b.
However, as shown in FIG. 6C, in the above described conventional multi-shaft turret type winding device, the touch roller 104 is shifted from a position where the plastic film 103 is contacted with the roll 103' to a different position when the winding mandrel 102a is exchanged for the winding mandrel 102b. Therefore, a wrinkled or improper portion occurs at the product roll 103' when air is permitted to be introduced into a portion between adjacent films of the product roll 103'. The wrinkled portion of the product roll 103' is not suitable as a product, and the product roll 103' therefore has to be unwound in order to remove the wrinkled portion after finishing a winding operation. This operation has negative influence on the productivity in forming the product roll 103'.
To resolve the above problem, another conventional winding device has been recommended as shown in FIGS. 7A, 7B and 7C. In this winding device, a plurality of touch rollers 104 are provided in order that the touch rollers 104 successively follow a product roll 103' while a winding mandrel 102a is exchanged for another winding mandrel 102b.
However, in this conventional winding device, the relative position of the product roll 103' with respect to the contacting touch roller 104 is not constant while the roll 103' is removed in order to exchange the positions of the winding mandrels 102a and 102b. As shown in FIGS. 8A and 8B, the plastic film 103 cannot be wound at an appropriate winding angle and the plastic film 103 is introduced to the winding mandrel 102a along a tangent line of the product roll 103'. Therefore, air is introduced between the layers of the plastic film 103 and wrinkled portions sometimes occur.
The purposes of the present invention are to resolve the above described problems and to provide a multi-shaft turret type winding device for winding a thin layer band material such as a plastic film without trapping air bubbles when the winding mandrel is changed for another winding mandrel.